Computer Architecture

Architecture & Organization

          Architecture is those attributes visible to the programmer
         Instruction set, number of bits used for data representation, I/O mechanisms, addressing techniques.
         e.g. Is there a multiply instruction?
          Organization is how features are implemented
         Control signals, interfaces, memory technology.
         e.g. Is there a hardware multiply unit or is it done by repeated addition?
          All Intel x86 family share the same basic architecture
          The IBM System/370 family share the same basic architecture
          This gives code compatibility
         At least backwards
          Organization differs between different versions

Structure & Function

          Structure is the way in which components relate to each other
          Function is the operation of individual components as part of the structure

Structure Top Level
Structure The CPU
Structure The Processor


Computer Evolution and Performance ENIAC – background

          Electronic Numerical Integrator And Calculator
          Eckert and Mauchly
          University of Pennsylvania
          Trajectory tables for weapons
          Started 1943
          Finished 1946
         Too late for war effort
·         Used until 1955

ENIAC – details

          Decimal (not binary)
          20 accumulators of 10 digits
          Programmed manually by switches
          18,000 vacuum tubes
          30 tons
          15,000 square feet
          140 kW power consumption
5,000 additions per second

von Neumann/Turing

          Stored Program concept
          Main memory storing programs and data
          ALU operating on binary data
          Control unit interpreting instructions from memory and executing
          Input and output equipment operated by control unit
          Princeton Institute for Advanced Studies
         IAS
·         Completed 1952

 
Structure of von Nuemann machine
Commercial Computers

          1947 - Eckert-Mauchly Computer Corporation
          UNIVAC I (Universal Automatic Computer)
          US Bureau of Census 1950 calculations
          Became part of Sperry-Rand Corporation
          Late 1950s - UNIVAC II
         Faster
·         More memory

IBM

          Punched-card processing equipment
          1953 - the 701
         IBM’s first stored program computer
         Scientific calculations
          1955 - the 702
         Business applications
          Lead to 700/7000 series

Transistors

          Replaced vacuum tubes
          Smaller
          Cheaper
          Less heat dissipation
          Solid State device
          Made from Silicon (Sand)
          Invented 1947 at Bell Labs
          William Shockley et al.

Transistor Based Computers

          Second generation machines
          NCR & RCA produced small transistor machines
          IBM 7000
          DEC - 1957
         Produced PDP-1

Microelectronics

          Literally - “small electronics”
          A computer is made up of gates, memory cells and interconnections
          These can be manufactured on a semiconductor
          e.g. silicon wafer

Generations of Computer

          Vacuum tube - 1946-1957
          Transistor - 1958-1964
          Small scale integration - 1965 on
         Up to 100 devices on a chip
          Medium scale integration - to 1971
         100-3,000 devices on a chip
          Large scale integration - 1971-1977
         3,000 - 100,000 devices on a chip
          Very large scale integration - 1978 to date
         100,000 - 100,000,000 devices on a chip
          Ultra large scale integration
          Over 100,000,000 devices on a chip

Moore’s Law

          Increased density of components on chip
          Gordon Moore - cofounder of Intel
          Number of transistors on a chip will double every year
          Since 1970’s development has slowed a little
         Number of transistors doubles every 18 months
          Cost of a chip has remained almost unchanged
          Higher packing density means shorter electrical paths, giving higher performance
          Smaller size gives increased flexibility
          Reduced power and cooling requirements
  •           Fewer interconnections increases reliability



Growth in CPU Transistor Count

IBM 360 series

          1964
          Replaced (& not compatible with) 7000 series
          First planned “family” of computers
         Similar or identical instruction sets
         Similar or identical O/S
         Increasing speed
         Increasing number of I/O ports (i.e. more terminals)
         Increased memory size
         Increased cost
          Multiplexed switch structure

Semiconductor Memory

          1970
          Fairchild
          Size of a single core
         i.e. 1 bit of magnetic core storage
          Holds 256 bits
          Non-destructive read
          Much faster than core
          Capacity approximately doubles each year

Intel

          1971 - 4004
         First microprocessor
         All CPU components on a single chip
         4 bit
          Followed in 1972 by 8008
         8 bit
         Both designed for specific applications
          1974 - 8080
         Intel’s first general purpose microprocessor

Speeding it up

          Pipelining
          On board cache
          On board L1 & L2 cache
          Branch prediction
          Data flow analysis
          Speculative execution

Performance Mismatch

          Processor speed increased
          Memory capacity increased
          Memory speed lags behind processor speed

DRAM and Processor Characteristics

Solutions

          Increase number of bits retrieved at one time
         Make DRAM “wider” rather than “deeper”
          Change DRAM interface
         Cache
          Reduce frequency of memory access
         More complex cache and cache on chip
          Increase interconnection bandwidth
         High speed buses
         Hierarchy of buses


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